1. Field of the Invention
The present invention is broadly concerned with a method and apparatus designed to greatly facilitate addition of fluids to, or removal of fluids from, an internal body organ or part of an animal. More particularly, it is concerned with such a method and apparatus which is especially suited for the large scale production of monoclonal antibodies in large mammals, and which permits repeated monitoring and/or nutritional enhancement of the in vivo monoclonal antibody production procedure.
2. Description of the Prior Art
When a foreign substance enters the body of a vertebrate animal or is injected into it, one aspect of the immune response is the secretion by plasma cells of antibodies. Quite apart from the natural function of antibodies in the animal's immune response, such antibodies have long been an important tool for investigators, who capitalize on their specificity to identify or label particular molecules or cells and to separate them from a mixture. The antibody response to a typical antigen is normally highly heterogeneous, and even the best of antisera are really heterogeneous mixtures of many different antibody molecules that vary in charge, size, and in such biologic properties as the ability to fix complement or to agglutinate or precipitate antigen. It is extremely difficult to separate the various antibodies in antisera, and therefore conventional antisera contain mixtures of antibodies, and such mixtures vary from animal to animal.
It is also known that malignant tumors of the immune system (called myelomas) are characterized by rapidly proliferating cells producing large amounts of abnormal immunoglobulines called myeloma proteins. A tumor itself is considered to be an immortal clone of cells descended from a single progenitor, and so myeloma cells can be cultured indefinitely, and all the immunoglobulines they secrete are identical in chemical structure. They are in effect monoclonal antibodies, but there is no way to know what antigen they are directed against, nor can one induce myelomas that produce antibody to a specific antigen. However, in recent years researchers have learned how to fuse myeloma cells of mice with lymphocytes from the spleen of mice immunized with a particular antigen. The resulting hybridmyeloma, or "hybridoma" cells express both the lymphocyte's property of specific antibody production and the immortal character of the myeloma cells. Such hybrid cells can be manipulated by the techniques applicable to animal cells in permanent culture. Individual hybrid cells can be cloned, and each clone produces large amounts of identical antibody to the single antigenic determinant. The individual clones can be maintained indefinitely, and at any time samples can be grown in culture or injected into animals for large scale production of monoclonal antibody. Highly specific monoclonal antibodies produced by this general method have proved to be a versatile tool in many areas of biological research and clinical medicine.
While the utility of specific monoclonal antibodies is manifest, a problem has arisen because of the difficulty of producing significant (e.g., liter) quantities of the antibodies. Obviously, the production of such antibodies in mice is not at all suited for large scale production. In response to this problem, it has been suggested to employ large mammals such as cattle or sheep for in vivo production of monoclonal antibodies. Indeed, a very recent breakthrough in this area has demonstrated the usefulness of this approach, particularly in the context of monoclonal antibody production in a cow's uterus. In such a procedure, the cells of hybridoma clones are introduced into the uterus of a cow in the early stages of gestation, and are allowed to multiply. After a suitable growth period, an extremely large quantity of monoclonal antibodies can be harvested from the uterus. While the above described technique shows considerable promise, a number of practical problems remain. For example, it is desirable to monitor the production of monoclonal antibodies in the cow's uterus, and the problems of obtaining samples of the uterine fluid on a frequent recurrent basis are formidable. The straightforward procedure of simply making a laparotomy incision in the cow's body, manipulation of the uterus, introducing or withdrawing materials, can create multiple insults to the cow, uterus and fetus, thus traumatizing the cow, uterus and fetus, which may lead to premature death, infection, or abortion of the fetus. By the same token, in order to enhance antibody production in the cow's uterus, it is oftentimes desirable to introduce nutrient fluids into the uterus. Here again, the conventional techniques for such introduction, if used repeatedly, can cause severe problems to the animal and uterine environment.
It will therefore be seen that there is a real and unsatisfied need in the art for a method and apparatus which permits easy, rapid addition of fluids to, or removal of fluids from, specific body parts or organs of animals, so as to facilitate the monitoring and production of monoclonal antibodies while at the same time avoiding repeated insults to the animal and other internal organs.